Fix panic in BanksServer (#12293) (#12295)

Fixes #12167

(cherry picked from commit 3ecb390b10)

Co-authored-by: Greg Fitzgerald <greg@solana.com>

banks-server/src/banks_server.rs

@@ -23,7 +23,7 @@ use solana_sdk::{
 use std::{
     collections::HashMap,
     io,
-    net::SocketAddr,
+    net::{Ipv4Addr, SocketAddr},
     sync::{
         atomic::AtomicBool,
         mpsc::{channel, Receiver, Sender},
@@ -245,7 +245,12 @@ pub async fn start_tcp_server(
         .filter_map(|r| future::ready(r.ok()))
         .map(server::BaseChannel::with_defaults)
         // Limit channels to 1 per IP.
-        .max_channels_per_key(1, |t| t.as_ref().peer_addr().unwrap().ip())
+        .max_channels_per_key(1, |t| {
+            t.as_ref()
+                .peer_addr()
+                .map(|x| x.ip())
+                .unwrap_or_else(|_| Ipv4Addr::new(0, 0, 0, 0).into())
+        })
         // serve is generated by the service attribute. It takes as input any type implementing
         // the generated Banks trait.
         .map(move |chan| {